c. Alkali and salt
d. Acid and base
e. Strong base and weak base.
13. What is neutralization reaction? Write its application in our daily life.
14. What chemical is used when an ant bites? Why?
15. The problem of acidity in stomach is treated by taking solution of milk of magnesia.
Explain why?
1. Choose the correct alternatives from the following options.
i. Sulphuric acid is an example of...................
a. Organic acid b. Weak acid
c. Inorganic acid d. Base
ii. Molecular formula of milk of magnesia is:
a. Al2O3 b. Mg (OH)2
c. MgO d. None of the above
iii. Strong acid and weak base reacts to produce:
a. Acidic salt b. Neutral salt
c. Basic salt d. None of the above
iv. NH4Cl is an example of good ............... in dry cells:
a. electricity b. compound
c. solution d. electrolyte
v. Bases are generally:
a. Non-metal b. Sour
c. Tasteless d. Metal Oxides
Blooming Science Book 10 151
Chapter Some Gases
10
Antoine Lavoisier
1743 AD-1794 AD
Lesson Objectives Estimated Periods: 5+2
On the completion of this unit, the students will be able to:
State the principle of laboratory preparation of CO2 and NH3 gases.
explain the manufacturing process of these gases.
tell the physical and chemical properties of gases.
describe the various uses of Carbon dioxide and NH3.
Introduction
Carbon dioxide in air, though in very small amount, plays an important role in the continued existence
of life. In sunlight, green plants manufacture food from carbon dioxide and water. Living beings
depend upon the food thus prepared by the green plants either directly or indirectly. Obviously, if
all the carbon dioxide were removed from the air, all plants and animals would disappear.
It was prepared by Van Helmont in 1640AD for first time by burning wood. In 1755AD, Joseph
Black called it fired air. Lavoisier studied the properties of CO2 in 1783AD.
Molecular formula: CO2 Molecular mass: 44
Occurrence
Carbon dioxide constitutes about 0.03% to 0.04% of the air by volume. The proportion may
double or triple in a crowd places. Owing to the solubility of carbon dioxide in water, oceans and
lakes are the great reservoirs of this gas. In an accumulated form it is found sometimes in well,
caves and mines. It is present in the metallic carbonate such as calcium carbonate, zinc carbonate
(calamine), magnesium carbonate (magnesite) etc. Carbon dioxide gas is found in following
sources:
1. Burning of carbon containing fuel in industries, Scan for practical experiment
2. Respiration of all living beings,
3. Fermentation and decay,
4. Volcanic eruption and
5. Exhaust of automobiles.
Carbon dioxide gas is found in air as molecules. Each carbon dioxide visit: csp.codes/c10e12
molecule contains two sets of double bonds because carbon atom
shares two electron pairs with each of two oxygen atoms.
152 Blooming Science Book 10
8p+ 6p+ 8p+
8n 6n 8n
Molecular structure of carbon dioxide
Laboratory Preparation of Carbon dioxide
In the laboratory, carbon dioxide is prepared by the action of dilute hydrochloric acid on calcium carbonate
(usually in the form of marble or chalk). Marble is a pure form of calcium carbonate found in nature.
Method
A few pieces of marble chips are taken in a Woulfe’s bottle. The bottle is fitted with thistle
funnel and a delivery tube. Water is poured down the thistle’s funnel until it covers the marble
chips. Dilute hydrochloric acid is poured down the thistle funnel. As soon as acid comes in
contact with marble chips, brisk effervescence takes place due to release of carbon dioxide. The
gas is collected by the upward displacement of air as it is heavier than air.
Dilute Hydrochloric acid
Thistle funnel Delivery tube
Woulfe’s bottle
Gas jar
Marble pieces Carbon dioxide gas
Fig: laboratory Preparation of carbon
Note: Dilute sulphuric acid should not be used for the laboratory preparation of carbon
dioxide gas because calcium sulphate so formed being insoluble will cover the
calcium carbonate and stops reaction further. Calcium carbonate is preferred to other
carbonates because the commercial variety is cheap and easily available.
Test of carbon dioxide
1. In order to know whether the gas jar is full, bring a lighted match stick near the mouth of
the gas jar. If it is extinguished, the gas jar is full of CO2.
2. It turns lime water milky due to the formation of a white insoluble calcium carbonate.
Blooming Science Book 10 153
3. Moist blue litmus paper is inserted in the gas jar it changes into red as it is audic in nature.
4. Burning magnesium ribbon burns continuously forming white dust (MgO) and black dust
of carbon.
Precautions
1. The apparatus must be air tight.
2. Thistle funnel must be dipped in the acid but end of delivery tube should not touch the acid
inside Woulfe’s bottle.
General methods of preparation of carbon dioxide
1. Carbon burns in oxygen of air to form carbon dioxide.
Carbon + Oxygen → Carbon dioxide
C + O2 → CO2
2. Various hydrocarbons such as methane, ethane, butane etc. burn in air to form carbon
dioxide. Scan for practical experiment
Methane + Oxygen
→ Carbon dioxide + Water
CH4 + 2O2 → CO2 + 2H2O
Ethane + Oxygen → Carbon dioxide + Water
2C2H6 + 7O2 → 4CO2 + 6H2O
3. By the reaction of acid and carbonate bicarbonates visit: csp.codes/c10e13
Carbon dioxide is also formed by the action of dilute acids on carbonates and bicarbonates
of metals.
Sodium carbonate + Hydrochloric acid → Sodium chloride + Water + Carbon dioxide
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
Sodium bicarbonate + Hydrochloric acid → Sodium chloride + Water + Carbon dioxide
NaHCO3 + HCl → NaCl + H2O + CO2
Calcium carbonate + Hydrochloric acid → Calcium chloride + Water + Carbon dioxide
CaCO3 + 2HCl → CaCl2 + H2O + CO2
Calcium bicarbonate + Hydrochloric acid → Calcium chloride + Water + Carbon dioxide
Ca(HCO3)2 + 2HCl → CaCl2 + 2H2O + 2CO2
Manufacture of Carbon dioxide
A limestone found in nature contains calcium carbonate. The limestone are piled at a place and
heated either by coal or firewood. Calcium oxide and carbon dioxide are released. Thus, released
carbon dioxide is collected and used for industrial purposes.
154 Blooming Science Book 10
Calcium Carbonate Heat Calcium oxide + Carbon dioxide
CaCO3 ∆ CaO + CO2
Calcium oxide is called lime or quick lime. If a few drops of water is added to a piece of quick
lime, the solid crumbles to powder swelling up to almost four times its original volume and
becomes very hot. The powder formed is calcium hydroxide which is also called slaked lime.
Calcium oxide + Water → Calcium hydroxide
CaO + H2O → Ca(OH)2
The solution of slaked lime turns red litmus blue. Lime water is prepared by mixing 2 to 3 grams
of slaked lime in one litre of water. The solution is kept undisturbed for about an hour. The slaked
lime and lime water are chemically the same substance. The former is solid and later is a solution.
Physical Properties
1. It is a colourless and odourless gas with slight acidic taste when dissolved in water.
2. It changes moist blue litmus paper into red.
3. It is heavier than air. It is about 1.5 times heavier than air. As such it can be poured from
one jar to another.
4. It is fairly soluble in water under pressure.
5. It liquefies at ordinary temperature i.e. at about 20oC
under about 70 atmospheres. It is liquified at about -78oc
to form white solid called as dry ice.
6. It is not poisonous but since it does not support Carbon dioxide
respiration, living beings die due to suffocation in an Air
atmosphere of carbon dioxide due to lack of oxygen
7. Its boiling point is 0oC at 40 atm and freezing point is
-78oC.
Chemical Properties
1. Carbon dioxide when dissolves in water forms carbonic acid. Carbonic acid turns blue
litmus to red.
Carbon dioxide + Water Carbonic acid
CO2 + H2O high pressure H2CO3
low pressure
Carbonic acid is a weak acid; only a few of its molecules ionize to produce hydrogen ions.
H2CO3 HCO3- + H+
2. Carbon dioxide is neither combustible nor supporter of combustion. Hence a burning
splinter is extinguished at the gas does not burn, when lowered into the jar of carbon
dioxide. However, burning magnesium ribbon when introduced into a jar of carbon dioxide,
it continues to burn forming a white powder solid, magnesium oxide and black specks of
carbon which get deposited on the sides of the gas jar.
Blooming Science Book 10 155
Burning magnesium Jar containing carbon dioxide
Black specks of carbon
Burning magnesium in carbon dioxide gas
Magnesium + Carbon dioxide → Magnesium oxide + Carbon
2Mg + CO2 → 2MgO + C
3. Being an acidic oxide, it neutralizes alkalis like sodium hydroxide and potassium hydroxide to
form carbonate (a salt) and water.
Sodium hydroxide + Carbon dioxide → Sodium carbonate + Water
2NaOH + CO2 → Na2CO3 + H2O
Potassium carbonate + Water
Potassium hydroxide + Carbon dioxide →
2KOH + CO2 → K2CO3 + H2O
4. When carbon dioxide is passed through clear lime water, it turns milky. This is due to
the formation of white suspension of insoluble calcium carbonate.
Lime water + Carbon dioxide → Calcium carbonate + Water
Ca (OH)2 + CO2 → CaCO3 + H2O
On bubbling more carbon dioxide gas in above suspension, the milky solution becomes
clear due to the formation of soluble calcium bicarbonate.
Calcium carbonate + Water + Carbon dioxide → Calcium bicarbonate
CaCO3 + H2O + CO2 → Ca(HCO3)2
This reaction is used as a test for carbon dioxide gas
5. Atmospheric carbon dioxide and water are used by green plants in the presence of sunlight
to prepare carbohydrate. This process is called photosynthesis.
Carbon dioxide + Water Chlorophyll
Sunlight carbohydrate + Oxygen
6CO2 + 6H2O Chlorophyll C6H12O6 + 6O2
Sunlight
6. Carbon dioxide reacts with red hot coke at about 900oC to form carbon monoxide.
CO2 + C → 2CO
7. Carbon dioxide reacts with ammonia at about 1500oC temperature and under pressure
to form urea, a chemical fertilizer
Carbon dioxid + Ammonia 1500oc Urea + water
CO2 + 2NH3 1500oc NH2− CO −NH2 + H2O
156 Blooming Science Book 10
Uses
1. It is used in making aerated drinks such as soda water, lemonade, coca cola, etc. Soda
water is water containing dissolved carbon dioxide.
2. It is used to extinguish fire because it is neither combustible nor helps in combustion and
being heavier than air it settles down on the burning surface and formed a layer cutting off
the supply of air (O2) to fire.
3. Liquid carbon dioxide is used in carbonation process in sugar industry.
4. It is used to manufacture urea, a chemical fertilizer.
5. Mixture of oxygen and carbon dioxide (10-15%) is called carbogen which is used to
provide artificial respiration to patient from pneumonia. Carbon dioxide increases the rate
of respiration.
6. Cakes and bread swells up on being baked because carbon dioxide produced from baking
powder causes bread to rise.
7. The solid form of carbon dioxide dry ice is used as a refrigerant in the edible of eatable
goods or food stuffs.
8. It is used by green plants during photosynthesis to prepare carbohydrates and oxygen.
Let's Learn
1. Carbon doixide solution has acidic nature because when CO2 is dissolved in water, it
forms carbonic acid which turns blue litmus paper into red.
2. There is no trough containing water in lab preparation of CO2, it is because CO2 is soluble
in water and forms H2CO3.
3. Bubbles come out when coca cola bottles are opened. It is because in manufacture of
coke, CO2 is dissolved at extreme pressure. When the lid of bottle is opened, the pressure
reduces and CO2 comes out in the form of bubbles.
4. When CO2 is added to limewater, it turns into milky. It is because there is formation of
CaCO3 which is insoluble in water and white in colour.
Points to Remember
1. Carbon dioxide gas is prepared in the laboratory by treating marble chips with dilute
hydrochloric acid.
CaCO3 + 2HCl CaCl2 + CO2↑ + H2O
2. It is manufactured by heating limestone.
CaCO3 ∆ CaO + CO2
3. Carbon dioxide is soluble in water and makes a weak acid.
H2O + CO2 H2CO3
4. Carbon dioxide turns lime water into milk, milky colour disappears on passing excess of
carbon dioxide thought it.
5. Solid carbon dioxide is called dry ice. It is used as a preservatives.
6. Carbon dioxide is mainly used as a fire extinguisher.
Blooming Science Book 10 157
Project Work
To make a fire extinguisher.
Take a bottle fitted with a bent jet tube. Fill three fourth of the bottle with Conc, H2So4
concentrated baking soda solution. Take a test tube containing conc sulphuric
acid and suspend it in the bottle with the help of a thread in such a way that NaHCO3
when the bottle is inclined, acid present in the test tube gets mixed with the (solutions)
baking soda solution. Carbon dioxide is produced. Bring the jet near the
burning candle, it extinguishes. Fig: Fire extinguisher
Sodium bicarbonate+Sulphuric acid→Sodium sulphate+Water+Carbon dioxide
2NaHCO3 + H2SO4 → Na2SO4 + 2H2O + 2CO2
Exercise
1. Write the principle for the preparation of carbon dioxide in the laboratory and also
draw a labelled diagram of the fitted apparatus used.
2. What are the chemical names of Chalk, Quicklime and Slaked lime? Give two differences
between Quicklime and Slaked lime.
3. Explain the following:-
(a) Carbon dioxide is not a supporter of combustion, yet burning magnesium continues
to burn in it.
(b) Carbon dioxide is much more soluble in alkaline solutions.
4. What happens when (explain with balanced chemical equation)
(a) Carbon dioxide is passed into clear lime water.
(b) Carbon dioxide is continuously passed through lime water.
(c) A burning magnesium ribbon is introduced into gas jar containing carbon dioxide.
(d) Balloon filled with CO2 is released in air.
5. What property of carbon dioxide enables us to be used to put out fires and be collected by
upward displacement of air in a gas jar?
6. Photosynthesis is a process which involves water along with sunlight and chlorophyll.
(a) Which gas in the atmosphere is involved in the reaction?
(b) Which gas is produced in the reaction?
(c) What type of organic compound is produced in the reaction?
(d) Write down its chemical equation.
158 Blooming Science Book 10
7. Complete the following equations.
(a) Carbon dioxide + → Carbonic acid
(b) + Carbon dioxide → Magnesium oxide + Carbon
(c) Calcium carbonate → + Carbon dioxide
8. What is the action of water on quicklime. Write an equation to show this reaction.
9. When carbon dioxide is poured into a beaker, the candles are Carbon dioxide
extinguished in turn as shown in the diagram. What
conclusion can be drawn from this experiment?
10. What happens to blue litmus paper when it is dipped in water containing carbon dioxide,
give reason?
11. Write short note on:
(a) Photosynthesis (b) Dry Ice
(c) Fire Extinguisher (d) Manufacture of Carbon dioxide
12. The figure below shows the fitted apparatus required to
prepare a gas in the laboratory. Study the figure and answer the Dilute Hydrochloric acid
question that follow:
(a) Which gas is being collected in the jar?
(b) Write the balanced chemical equation of the chemical Marble
reaction that takes place during the gas preparation. pieces
(c) Why is the gas jar kept dry and upright?
13. Carbon dioxide dissolves in water to form carbonic acid, which is a weak acid. Write
equation to show this reaction.
Blooming Science Book 10 159
Ammonia
Introduction
Molecular Formula = NH3 Molecular mass = 17
Occurrence
Ammonia is compound gas made by one nitrogen and three 1p+ 7p+ 1p+
hydrogen atoms. It was first prepared by lavoisier by heating 7n
ammonium chloride (Sal ammoniac). Later on, Bertrelot and Davy
studied about its composition
Small quantities of ammonia are found in air in localities where 1p+
nitrogenous organic matter decays. In the combined state, it occurs
in nature as ammonium sulphate and ammonium chloride. The sharp characteristic smell which
one meets near a decaying heap or organic matter or urinal, which has not been cleaned, is due
to ammonia.
Laboratory Preparation of Ammonia
Ammonia is usually prepared in the laboratory by heating a mixture of dry solid ammonium
chloride (Sal-ammoniac) and Slaked lime (Calcium hydroxide) in 2:1 ratio.
Ammonium chloride + Calcium hydroxide → Calcium chloride + Water + Ammonia
2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3
Method
A finely grinded mixture of ammonium chloride 2 part and slaked lime 1 parts is taken in a hard
glass test tube . A cork carrying a delivery tube bent upward is fitted. The free end of the delivery
tube is introduced in an inverted dry gas jar supported by a stand as shown in the figure. On
heating the mixture, ammonia gas is released.
The released ammonia gas is passed through tower packed with quick lime (CaO). Quick lime
absorbs moisture. It is a dehydrating agent. CaO + H2O → Ca(OH)2
Dry ammonia is collected in an inverted gas jar by downward displacement of air as:
ammonia is highly soluble in water and lighter than air.
Hard glass test tube Gas jar
Ammonia gas
Mixture of
ammonium Delivery tube
chloride and
calcium hydroxide
Burner Drying tower
packed with
quick lime
(Lime tower)
Fig: Laboratory preparation of dry ammonia
160 Blooming Science Book 10
Tests
1. It is a colourless gas with a characteristic pungent smell.
2. It turns moist red litmus paper into blue. This indicates the basic nature of ammonia.
3. It gives dense white fumes of ammonium chloride when a glass rod dipped in concentrated
hydrochloric acid is held in the ammonia gas.
Precautions
1. Hard glass test tube must be slightly inclined.
2. The gas jar must be dry.
3. The apparatus must be air tight.
Since water is formed in the above reaction, the hard glass test tube is kept in an inclined
position to prevent the water from trickling back into the heated test-tube.
General methods of preparation of Ammonia
1. By heating ammonium salts with strong bases
Ammonia is prepared by warming ammonium salts with alkalis.
Ammonium sulphate + Slaked lime → Calcium sulphate + Water + Ammonia
(NH4)2SO4 + Ca(OH)2 → CaSO4 + 2H2O + 2NH3
Ammonium chloride + Potassium hydroxide → Potassium chloride + Water + Ammonia
NH4Cl + KOH → KCl + H2O + NH3
2. By heating ammonium salts
Ammonia is also prepared by heating ammonium salt alone.
Ammonium carbonate ∆ Ammonia + Water + Carbon dioxide
(NH4)2CO3 ∆ 2NH3 + H2O + CO2
3. By the reaction of metal nitride and hot water
Ammonia gas is also prepared in the laboratory by the action of hot water on a metal
nitrides such as magnesium nitride or aluminium nitride. Nitrides are readily decomposed
by hot water to give ammonia.
Magnesium nitride + Water → Magnesium hydroxide + Ammonia
Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3
Industrial Manufacture of Ammonia (Haber’s Synthesis)
The most important process for the production of ammonia involves its synthesis from nitrogen
and hydrogen under special conditions. The process is called Haber’s process. In Haber’s process
nitrogen and hydrogen combine to form ammonia. Nitrogen is available from the atmosphere
and hydrogen from natural gas. The reaction is carried out at high temperature and pressure.
Blooming Science Book 10 161
N2 + H2
Reaction chamber Cooling chamber
N2 + H2 Fe and Mo
(1 : 3) 500oC
Electric spark
Liquid ammonia
Fig: Industrial Manufacture of Ammonia by Haber’s process
High temperature is produced by electric spark. At high temperature of 500OC, 200 atmospheric
pressure and in the presence of catalyst iron and promoter molybdenum nitrogen and hydrogen
(1 : 3) combine to form ammonia.
N2 + 3H2 200 – 300 atm 2NH3
500oC (Fe–Mo)
The ammonia formed is circulated through the cooling chamber until it cools sufficiently and
liquefies. The liquid ammonia is called liquor ammonia.
Today about 85% of the ammonia produced in the world is used to make fertilizers.
Physical Properties
1. It is a colourless gas.
2. It has a characteristic pungent (bad) odour which brings tears into the eyes.
3. It is lighter than air.
4. It is highly soluble in water.
5. It is basic in nature, it turns moist red litmus paper into blue.
6. Its boiling point is -33.4oC and freezing point is -78oC.
Chemical Properties
1. Ammonia is basic in nature. It reacts with acids to form corresponding ammonium salts.
Ammonia reacts with hydrogen chloride gas to produce white fumes of ammonium
chloride. This reaction can be used to test the ammonia gas.
Ammonia + Hydrochloric acid → Ammonium Chloride
NH3 + HCl → NH4Cl
Ammonia reacts with dilute sulphuric acid to form ammonium sulphate.
Ammonia + Sulphuric acid → Ammonium sulphate
2NH3 + H2SO4 → (NH4)2 SO4
Ammonia reacts with dilute nitric acid to form ammonium nitrate.
NH3 + HNO3 → NH4NO3
2. Reaction with water:- Ammonia is highly soluble in water. It dissolves in water to form
ammonium hydroxide which is a weak alkali.
Ammonia + Water → Ammonium hydroxide
NH3 + H2O → NH4OH
162 Blooming Science Book 10
Ammonium hydroxide is an alkali and an electrolyte showing the presence of ions. The
ions present in ammonium hydroxide are NH4+ and OH-.
Ammonium hydroxide turns red litmus blue. It neutralizes an acid to form salt. Ammonium
hydroxide reacts with acids like suplhuric acid, hydrochloric acid and nitric acid to form
respective ammonium salts along with water.
Ammonium hydroxide + Hydrochloric acid → Ammonium chloride + Water
NH4OH + HCl → NH4Cl + H2O
3. Ammonia is a strong reducing agent. It reduces hot copper oxide to copper and lead oxide
to lead.
Ammonia + Copper oxide → Copper + Water + Nitrogen
2NH3 + 2CuO → 2Cu + 2H2O + N2
Ammonia + Lead oxide → Lead + Water + Nitrogen
2NH3 + 2PbO → 3Pb + 3H2O + N2
4. Ordinary ammonia is neither combustible nor a supporter of combustion. However, it
burns in oxygen with a greenish yellow flame producing water vapour and free nitrogen.
Ammonia + Oxygen → Nitrogen + Water
4NH3 + 3O2 → 2N2 + 6H2O
5. Ammonia reacts with carbon dioxide at a temperature of about 1500OC under certain
pressure to form urea. Urea is an important fertilizer.
Ammonia + Carbon dioxide → Urea + Water
2NH3 + CO2 → NH2-CO-NH2 + H2O
Uses
1. It is used in the manufacture of nitrogenous fertilizers such as ammonium sulphate,
ammonium phosphate, ammonium nitrate, urea, etc. Sometimes liquid ammonia is applied
directly to the soil.
2. It is used in the manufacture of nitric acid. It is an important industrial chemical.
3. It is also used for the manufacture of certain dyes, explosives and plastics.
4. Liquid ammonia is also used as a refrigerant in the factories, cold storage etc.
5. Liquid ammonia is an important solvent. It is useful for cleaning oven and cookers.
6. It is used to develop the blue print of the maps.
7. It is also used in the manufacture of sodium carbonate (washing soda).
Let's Learn
1. Ammonia gas can not be collected over water because it is readily soluble and after
dissolving in water, it forms NH4OH.
2. When ammonia is dissolved in water, the solution has basic nature because it turns red
litmus paper into blue.
Blooming Science Book 10 163
3. The hard glass test tube is kept inclined in lab preparation of ammonia. It is
because the steam is formed while heating the mixture of ammonium chloride and
calcium hydroxide and finally forms water droplets. The inclined position prevents from
the cracking of the test tube.
Points to Remember
1. In laboratory ammonia gas is prepared by heating the mixture ammonium chloride and
calcium hydroxide
2NH4Cl + Ca(OH)2 2NH3↑ + CaCl2 + H2O
2. Ammonia is highly soluble in water so is not collected by downward displacement of water.
3. Ammonia is manufactured by heating nitrogen and hydrogen under certain conditions
called Haber’s process.
N2 + 3H2 500oC, Fe/Mo 2NH3
200 atm
4. Ammonia dissolves in water to form alkaline ammonium hydroxide.
NH3 + H2O NH4OH
5. Ammonia reacts with carbon dioxide on heating to form Urea.
2NH3 + CO2 NH2 - CO - NH2 + H2O
Project Work
Fountain Experiment
High solubility of ammonia in water can be demonstrated by the Fountain Experiment.
Procedure: A perfectly dry round Round bottom flask
bottomed flask is filled with ammonia. containing ammonia
A cork carrying a dropper is filled with Blue fountain
water and a tube ending in a jet is fitted Ammonia solution
in its mouth as shown in figure. The
flask is held in inverted position with Dropper
one end of the tube under red litmus Beaker
solution in a beaker. A few drops of Red litmus solution
water are introduced into the flask by
means of a dropper. Fig: Fountain experiment
Observation: The litmus solution rushes
out in the form of the blue fountain
inside the flask from the jet end of the
tube.
Conclusion: The water introduced into the flask absorbs the gas inside. This produces partial
vacuum. The atmospheric pressure pushes the red litmus solution in a beaker up through the
tube. The red litmus solution is turned blue since ammonia solution is alkaline.
164 Blooming Science Book 10
Exercise
1. How can ammonia prepared in the laboratory be converted into a nitrogenous fertilizer?
2. Ammonia gas is manufactured from nitrogen and hydrogen.
a) State one possible source of each gas and indicate how it is obtained.
b) Give the conditions of temperature and pressure for a high yield of ammonia.
c) Name the catalyst used.
d) Give two uses of ammonia.
3. Write the molecular formulae of urea and ammonium sulphate.
4. What happens when magnesium nitride is warmed with water? Name the gas evolved and
give a balanced equation for the same.
5. State what you see when a piece of moist red litmus paper is placed in a gas jar of ammonia.
6. Ammonia can be prepared by heating an ammonium salt with an alkali in the lab.
a. Name a pair of reagents suitable for this reaction.
b. Give the full equation for this reaction.
c. Draw a diagram of apparatus suitable for preparing dry ammonia gas.
d. Write down the properties of ammonia.
7. Which property of ammonia is demonstrated by the Fountain experiment?
8. Explain why?
a. When a glass rod dipper in hydrochloric acid is introduced in a gas jar full of
ammonia, dense white fumes are produced.
b. On inverting a jar of ammonia in a trough of water, it quickly gets filled with water.
c. Ammonia gas obtained is collected by the downward displacement of air.
d. Ammonia is not collected over water in the laboratory?
9. Explain why a fertilizer containing an ammonium salt gets spoiled if accidentally mixed
with calcium hydroxide solution?
10. Complete the following chemical equations and balance them.
i) N2 + …………… ⇒ NH3
ii) NH3 (g) + H2O (l) ⇒ …………….
iii) …………. + H2SO4 ⇒ (NH4)2SO4 + ………….
11. What is the catalyst used to make ammonia industrially? What is the advantage of
compressing hydrogen and nitrogen during the Haber’s process.
Blooming Science Book 10 165
12. Observe the diagram of an experiment and answer the following questions.
i) Name the gas present inside the round Round bottom flask
bottom flask. containing ammonia
ii) What change in colour of water inside the Blue fountain
tube within the flash is observed? Ammonia solution
iii) What is the reason for rising of water in the Dropper
tube?
Beaker
iv) Under what condition is the fountain Red litmus solution
observed inside the flask?
v) What is the purpose of adding few drops of
red litmus solution in water?
13 The diagram is an arrangement of an apparatus used for the preparation of ammonia
gas in the laboratory. Answer the following questions:
i) Write the balanced chemical equation of the reaction that occurs.
ii) Why is the hard glass test tube containing the mixture kept inclined?
iii) How is the gas collected? Explain with reason.
Mixture of ammonium chloride Hard glass test tube Ammonia gas
and calcium hydroxide
Gas jar
Burner Delivery tube
Stand
14. The diagrams below show the method to collect gases in the laboratory.
i) Name the gases that will collect in A and B.
ii) What happens if these gases are collected over
water? Explain.
A B
15. Choose the correct alternatives from the following options.
i. Carbon dioxide gas is slightly:
a. Neutral b. Basic
c. Acidic d. None of the above
166 Blooming Science Book 10
ii. Which gas is used to manufacture fertilizers?
a. Carbon dioxide b. Ammonia
c. Hydrogen d. All of the above
iii. What is the conclusion of fountain experiment?
a. Ammonia is highly soluble in water
b. Carbon dioxide is highly soluble in water
c. Ammonia is lighter than air
d. All of the above
iv. The molecular formula of baking soda is:
a.NaOH b. Na2CO3
v. c. NaCl d. NaHCO3
What happens in the colour of moist red litmus when it is brought close to ammonia?
a. Remains same b. Turn blue
c. Turn yellow d. All of the above
Blooming Science Book 10 167
Chapter Metals Henery James Brooke
1771 AD-1857 AD
11
(An English Crystallographer)
Learning Outcomes Estimated Periods: 6+2
On the completion of this unit, the students will be able to:
explain the important natural metals like iron, aluminium, copper, silver and gold.
mention various ores of metal for their extraction.
describe the metals by identifying physical properties.
write the uses of metals in our daily life.
The word metal is derived from Greek word metallon (metallou) which means mine or quarry.
Metal is an element, compound or alloy that is a good conductor of heat and electricity. Metals
are usually malleable and shiny. In metal atoms readily lose electrons to form positive ions
(cations). Those ions are surrounded by delocalized electrons, which are responsible for the
conductivity. The solid thus produced is held by electrostatic interactions between the ions and
the electrons cloud, which are called metallic bond.
Metals always have less than four valence electrons and their valency is also less than four.
It is very interesting to know that all the metals are produced by nucleosynthesis in stars or
supernovae. The sun and the Milky Way galaxy are composed by about 2% metals.
Metals used in our every field of life have great significance. Stainless steel is an alloy of iron,
chromium and carbon. It is used to make weapons, vehicles and many household utensils.
Some metals like silver, gold, copper, etc. are the coinage metals that are used in jewelry. Iron,
aluminium, copper, zinc, tin, lead, etc are widely used in industries. Similarly metals are also
used for making aeroplane, wire, sharp tools, etc.
In this unit, we will study about the ores of different metals, extraction of metals from ores,
properties and uses of some metals.
Minerals and Ores
Metals are mostly found in the combined state in nature. Sometimes, metals like Cu, Ag, Au, Hg
and Pt are found in native or in free state. All the other metals are found in the combined state as
minerals. Minerals are the naturally occurring substances in which certain metals are associated in
the form of compound with impurities. Cuprite (Cu2O), horn silver (AgCl), hydrated aluminium
silicate (Al2O3. 2SiO2. 2H2O), etc. are some common examples of minerals.
Ores are the naturally occurring substances or minerals from which metals can be conveniently and
economically extracted. For example, bauxite (Al2O3. 2H2O) is the most important and chief ore
of aluminium. Some other minerals containing ores of aluminium are cryolite (Na3AlF6), feldspar
(KAlSi3O8), etc. In this way, all ores are accordingly minerals but all minerals are not ores.
168 Blooming Science Book 10
Some Important Metals
Aluminium
Aluminium was first isolated by Wholer in the year 1827 A.D. It is the third
most abundant element in the earth’s crust. It is a bluish white metal with a
bright luster.
Symbol : Al Atomic No. : 13 [2, 8, 3]
Al
Atomic mass : 27 Valency : 3
Scan for practical experiment
Electronic Configuration
Shell K LM
No. of electrons
283
Orbitals
1s2 2s2, 2p6 3s2, 3p1
Position in the Periodic Table
Group: III A
Period - 3rd
Block - p-block visit: csp.codes/c10e14
Occurrence
Aluminium is not found in free state. But, in the combined state, it is abundantly found in the
earth’s crust and constitutes about 7.3% of it. The important ores of aluminium are:
1. Bauxite: Al2O3. 2H2O
2. Feldspar: K(AlSi3.O8)
3. China clay: Al2O3.2SiO2.2H2O
4. Cryolite: Na3AlF6
Among these ores, aluminium is extracted from bauxite ore as it is easily available in nature.
Physical properties
1. Aluminium is a silivery white shining metal.
2. It is light and its specific gravity is 2.7.
3. Its melting point is 660oC and boiling point is 1800oC.
4. It is a good conductor of heat and electricity.
5. It is highlt malleable and ductile.
Uses of Aluminium
1. Aluminium is used for making utensils, frames, electrical goods, construction materials, etc.
2. Its alloys are used for making sailboats, aircraft, automobiles, etc.
3. It is used for making aluminium foil for wrapping food, cigarette, pharamaceutical
products, etc.
4. It is used for making electric wire.
5. It is used for making coins.
Blooming Science Book 10 169
6. It is used for making alloys.
7. It is used for making silvery paints.
8. Being a good reflector, it is used for making mirrors for reflecting telescopes.
Iron
Iron is known from very ancient times of human civilization. It is the second most abundant
metal occurring in the earth’s crust.
Symbol : Fe Atomic No. : 26
Atomic mass: : 56 Valency : 2 and 3
Shell Electronic Configuration of Iron N
K LM 2
No. of electrons 2 8 14 4s2
1s2 2s2, 2p6 3s2, 3p6, 3d6
Orbitals
Position in the Periodic Table
Group : VIII
Period : 4th
Block : d-block
Occurrence
Iron is very rarely found in free state but it occurs in nature in combined form. It is found in
the body of living organisms. In blood it occurs as a part of haemoglobin. It is richly found in
different ores. The main ores of iron are as follows:
a. Haematite: Fe2O3
b. Magnetite : Fe3O4
c. Siderite: FeCO3
d. Limonite: Fe2O3. 3H2O
e. Iron pyrites FeS2
Among these ores, iron is extracted from haematite ore. Haematite ore contains maximum
amount of iron (about 72.5%) and abundantly found in the nature.
Physical properties of Iron
1. Pure iron is a grayish white and lustrous metal.
2. Its specific gravity is 7.86.
3. Iron melts at about 1500oC and boils at about 2500oC.
4. It is magnetic in nature but when temperature is more than 770oC.
5. It is a good conductor of heat and electricity.
6. It is malleable and ductile.
Uses of Iron
1. Iron is used for making rods, bolts, pipes, chains, vehicles, railway track, etc.
2. It is used for the manufacture of agricultural appliances, weapons and many other tools.
170 Blooming Science Book 10
3. It is used in the manufacture of steel.
4. It is used in making household utensils.
5. It is used as catalyst in different chemical reactions.
Copper
Copper has been known since pre-historic times. Its Latin name is Cuprum, which has been
derived from the Island of Cyprus.
Atomic symbol : Cu Atomic No. : 29
Atomic mass : 63.57 Valency : 1 and 2
Electronic Configuration of Copper
Shell KL M N
No. of electrons 1
28 18 4s1
Orbitals
1s2 2s2, 2p6 3s2, 3p6, 3d10
Position in the Periodic Table
Group : IB
Period : 4th
Block : d-block
Occurrence
Copper occurs in free as well as in combined states in the nature. In free state or in native state,
it is found in small amount. Some important ores of copper are given below.
1. Copper pyrite (Chalcopyrite) : CuFeS2
2. Cuprite (Ruby copper) : Cu2O
3. Copper glance (Chalcocite) : Cu2S
4. Malachite : CuCO3 . Cu(OH)2
5. Azurite : Cu(OH)2.CuCO3
Among these ores, copper is extracted from copper pyrite or chalcopyrite.
Physical Properties of Copper
1. Copper is reddish brown (flesh pink coloured ) metal with a metallic luster.
2. It is very a good conductor of heat and electricity.
3. Its specific gravity is 8.95.
4. Its melting point is 1083oC and boiling point is 2350oC.
5. It is highly malleable and ductile.
Uses of Copper
1. Copper is used for making electrical goods and cables.
2. It is used for making coins, jewelry, decorative objects and domestic utensils.
3. It is used in preparation of many useful alloys such as brass, bronze, german silver, etc.
4. It is used for electroplating and electrotypins.
5. It is used for the manufacture of dyes, pesticides, etc.
Blooming Science Book 10 171
Silver
Silver is known as coinage metal. It has been known to mankind since ancient time. The symbol
Ag for silver is derived from the Latin word Argentum. It is soft lustrous white metal.
Symbol : Ag Atomic No. : 47
Atomic mass : 107.88 Valency :1
Electronic Configuration of Silver
Shell KL M N O
No. of electrons 1
Orbitals 28 18 18 5s1
1s2 2s2, 2p6 3s2, 3p6, 3d10 4s2, 4p6, 4d10
Position in the Periodic Table
Group - IB
Period - 5th
Block - d-block
Occurrence
Silver occurs in free state as well as in combined state. Some of the important ores of silver are
as follows:
1. Argentite or silver glance: Ag2S
2. Silver copper glance: (AgCu)2S
3. Horn silver: AgCl
4. Pyrargyrite (Ruby silver) Ag3, SbS3
Among these ores, silver is extructed from its argentite are:
Physical Properties
1. Silver is a white lustrous metal.
2. Its specific gravity is 10.5.
3. Its melting point is 960oC and boiling point is 1955oC.
4. It is a very good conductor of heat and electricity.
5. It is highly malleable and ductile.
Uses of Silver
1. Silver is used to make coins, jewellery and decorative articles.
2. It is used in the preparation of silver salts and medicines.
3. It is used for silvering mirror.
4. Silver bromide is used in photography.
5. It is used in electroplating or silver plating.
6. Dentists fill cavities of teeth with silver amalgam (a mixture of silver, tin and mercury)
7. Silver nitrate and other silver compounds are used.
172 Blooming Science Book 10
Gold
Gold is known as coinage metal and mankind has known it since ancient time. The symbol Au
for gold is derived from the Latin word ‘Aurum’.
Symbol : Au Atomic No. : 79
Atomic weight : 197.2 Valency : 1 and 3
Electronic Configuration
Shell KL M N OP
No of electrons 2 8 18 32 18 1
Orbitals 1s2 2s2, 2p6 3s2, 3p6, 3d10 4s2, 4p6, 4d10, 4f14 5s2, 5p6,5d10 6s1
Position in the Periodic Table
Group - IB
Period - 6th
Block - d-block
Occurrence
Gold is a noble metal usually occurs in native state either mixed with quartz in rocks (reef gold) or
in alluvial sand. Gold is extracted from alluvial sand that is rich in gold.
Extraction of Gold from Alluvial Sand
The alluvial sand containing gold is carried in a sluiceway system where a strong current of water
is passed over it. A sluice way system is an inclined channel provided with through and cross wire
strips called riffles. The heavier gold particles are retained in the sluices while the water carries the
lighter particles of sand away. In this way gold is extracted from the alluvial sand. This process is
called placer mining process. It can also be extracted by panning process in small scale.
Physical Properties of Gold
1. Gold possesses a lustrous yellow colour.
2. It has melting point 1063oC and boiling point 2530oC.
3. It is heavy metal with a specific gravity of 19.3.
4. It is a best conductor of heat and electricity.
5. It is highly malleable and ductile.
Uses of Gold
1. Gold is used for making jewellery, coins and medals.
2. It is used for electroplating / gold plating.
3. It is used for making many gold salts, such as auric chloride which is used in electroplating
and photography (black and white) as a toning agent.
4. It is used for making gold leaf electroscope.
5. It is used for preparing alloys.
6. It is used in dentistry to coat teeth (crown bridge)
Occurrence of Metals in Nepal
More than 80 types of minerals are reported in large amount in different parts of Nepal. The name
of metals and their minerals and the place of occurrence of them in Nepal are tabled below.
Blooming Science Book 10 173
Occurrence of ores of Metals in Nepal
Metals Names of ores Places of occurrence
Iron
Magnetite Phulchoki-Lalitpur, Tanahun, Bhojpur,
Copper Haematite Ramechhap, Pyuthan, Chitwan
Gold Copper ores in the form of Udayapur, Dhading, Makawanpur,
Magnesium chalcopyrite, copper bronite Solukhumbu
Zinc/lead
Cobalt Alluvial gold Rapti river, Kali Gandaki river
Native gold Sunkoshi river, Swayambhu-Hall chowk area
Magnesite Udaypur, Dolakha
Lead-zinc deposit Ganesh Himal, Phulchoki
Cobaltite Palpa, Gulmi
Calcium Limestone Chobhar, Udayapur, Jogimara of Dhading
district, Okhre of Makwanpur
Bismuth Bismuth ore
Bhimphedi
Some alloys with their compositions and uses
Alloy Composition Uses
Brass Cu , Zn Medals, utensils
German Silver Cu, Zn, nickel Utensils
Bronze Cu, tin, Zn Coins, utensil
Gun Metal Cu, tin, Zn, Pd Making gun
Bell metal Cu, tin Bell
Stainless steel Fe, C, Chromium Making utensils
Let's Learn
1. Hot water does not attack aluminium. The aluminium exposes to air combines with O2 of
air a thin film of Al2O3 is formed at the surface of aluminium. This hard, tightly adhering
film of Al2O3 protects the aluminium from the corrosive action of hot water.
2. A moist iron piece left in air becomes reddish brown, it is because the moist iron combines
with atmospheric air and forms rust in the presence of iron.
4Fe + 2H2O + 3O2 2Fe2O3. 2H2O
3. Gold is found in free state or it is a noble metal because it doesn’t react with air, water, acid
and bases easily.
4. Aluminium is used to make body of aeroplane because it is light in weight and does not rust.
5. Pickles are not stored in a metallic vessel because pickles contain acids which react with
metal to form salt of that metal and destroy the pickles and vessel itself.
174 Blooming Science Book 10
Points to Remember
1. Metals are electropositive elements, which are shiny, generally heavy and good conductor
of heat and electricity.
2. Mineral is defined as a naturally occurring substance. It has a characteristic chemical
composition and, in general, a crystalline structure. Many names of minerals end in “-ite”.
3. From a naturally occurring mineral, a metal can be extracted, usually on a commercial basis.
4. Bauxite is the chief ore of aluminium, consisting of hydrated aluminium oxides.
5. Corrosion of metal is electro chemical attack on the surface of metal.
6. Coinage metals are a group of three malleable and ductile metals forming sub group-IB of
the periodic table. They are Cu, Ag and Au.
7. Copper pyrite, copper glance and cuprite are the main ores of copper.
8. Argentite is the principal ore for silver extraction.
9. Gold mainly occurs in free state or mixed with quartz or alluvial soil. However, the main
source of gold is alluvial soil.
Project Work
1. Make a list of items made up of metals found in your neighborhood.
2. React dilute HCl with thin plates of Al, Fe and Cu. What happens?
3. Observe by dissolving a copper plate into a solution of ferrous sulphate (FeSO4) and an
iron plate into a solution of copper sulphate (CuSO4). What happens? Why it happens
so?
Exercise
1. Write the difference between ore and mineral.
2. How does iron occur in nature?
3. Where is iron located in the periodic table? Write the electronic configuration of iron?
4. What do you mean by the extraction of metals?
5. What are the physical properties of iron? Why is iron called metal? Why is it not found in
free state?
6. List any two ores, uses and properties of the following metals:
a. iron b. aluminium c. silver
d. copper e. gold
7. What are the coinage metals? Why are they collectively called coinage metals?
8. Arrange the given metals in ascending order according to melting point and then according
to reactivity: Fe, Au, Ag, Al, Cu
9. Why are coinage metals grouped together in the periodic table?
10. What do you mean by noble metals?
11. What is the use of aluminium foils?
Blooming Science Book 10 175
12. Choose the correct alternatives from the following options.
i. What is the important ore of aluminium?
a. Haematite b. Bauxite
c. Cuprite d. Argentite
ii. Which one is also called as noble metal?
a. Iron b. Silver
c. Aluminium d. Gold
iii. Which metal has lowest density?
a. Aluminium b. Gold
c. Silver d. None of the above
iv. Chalcopyrite is an ore of:
a. Silver b. Copper
c. Iron d. Aluminium
v. Which of them are best examples of coinage metal?
a. Iron, Silver, Copper b. Copper, Gold, Iron
c. Copper, Silver, Aluminium d. Copper, Silver, Gold
176 Blooming Science Book 10
Chapter Hydrocarbon and Fridrich Wohler
Its Compounds 1800 AD-1882 AD
12 (Father of Organic)
Learning Outcomes Estimated Periods: 4+1
On the completion of this unit, the students will be able to:
explain saturated and unsaturated hydrocarbons.
identify alkanes, alkenes and alkynes
explain the types of alcohol and uses.
write the uses of ether, glycerol and glucose.
Introduction
Modern chemistry has been divided into a large number of branches viz. Inorganic, Organic,
Physical, Analytical, Nuclear, Biochemical, Industrial etc. However, about 300 years ago, it was
divided into two main branches Organic and Inorganic. Compounds originated from mineral
sources were named as inorganic materials and those obtained from animal or plant kingdom
were named as organic materials. Today the organic chemistry may be defined as the chemistry
of carbon compounds.
Organic Compounds
The compounds of carbon other than oxides of carbon, carbonates, bicarbonates and carbides
are called organic compounds. Organic compounds contain carbon and hydrogen. Other
elements like nitrogen, oxygen, halogens, sulphur etc. may be present in organic compounds.
Carbohydrate, protein, fat, petroleum, hydrocarbon, vegetable oil, plastics, synthetic fibers etc
are organic compounds.
Characteristics of Organic Compounds
a) Organic compounds are covalent compounds. They are usually poor conductors of
electricity and are not electrolyzed.
b) They have low melting point and boiling point.
c) They are highly combustible.
d) They are usually insoluble in water and soluble in organic solvents like ether, alcohol,
benzene, chloroform, hexane etc.
e) Organic compounds belonging to a particular group can be represented by the same
general formula.
Hydrocarbons
A compound made up of hydrogen and carbon only is called hydrocarbon. Methane (CH4),
ethane (C2H6), ethylene (C2H4), and acetylene (C2H2) are some examples of hydrocarbons
Blooming Science Book 10 177
because they are made up of only two elements: hydrogen and carbon. They obtained from the
underground oil deposits by drilling oil wells. The natural gas, which occurs above petroleum
deposits also contains hydrocarbons.
Hydrocarbons are classified into two groups:
(a) Saturated hydrocarbons
(b) Unsaturated hydrocarbons
Saturated Hydrocarbons (Alkanes): H HH
The hydrocarbons in which all the four valencies of a carbon HCH HC C H
atom are used as single covalent bonds are called saturated H HH
hydrocarbons. Saturated hydrocarbons are also called alkanes. Ethane
An alkane is a hydrocarbon in which the carbon atoms are Methane
connected by only single covalent bonds. There are no double or triple bonds in alkane. The
hydrocarbons such as methane (CH4), ethane (C2H6), propane(C3H8) and butane(C4H10) form a
series of compounds known as alkanes. The names of all these saturated hydrocarbons end with
‘ane’.
We can obtain the general formula of saturated hydrocarbons or alkanes by using the following
relation: CnH2n+2 where n is the number of carbon atoms in one molecule of the alkane.
If an alkane has 1 carbon atom in its molecule, then n = 1, and its molecular formula will be
C1H2x1+2 or CH4
If an alkane has two carbon atoms in its molecule, then n = 2, and its molecular formula will be
C2H2x2+2 or C2H6.
Saturated hydrocarbon (alkanes) are also called paraffins because they are chemically less
reactive (para = less, affins = affinity or reactivity).
Unsaturated Hydrocarbons (Alkenes and alkynes):
A hydrocarbon in which two carbon atoms are connected by a ‘double bond’ or a ‘triple bond’
is called an unsaturated hydrocarbon. Ethylene (H2C = CH2), and acetylene (HC ≡ CH) are two
important unsaturated hydrocarbons, because ethylene contains a double bond and acetylene
contains a triple bond between two carbon atoms.
HH
C=C
HH H C≡ C H
Ethylene Acetylene
(Contains a double bond) (Contains a triple bond)
Sharing two pairs of electrons between the two carbon atoms form a double bond whereas the
sharing of three electron pairs between two carbon atoms forms a triple bond. The unsaturated
hydrocarbons are obtained mostly from petroleum by a process called cracking. Ethylene is also
called ethene and acetylene is also called ethyne.
178 Blooming Science Book 10
Unsaturated hydrocarbons are of two types. They are:
1. Those containing double bonds (alkenes), and
2. Those containing triple bonds (alkynes).
1. Alkene: An unsaturated hydrocarbon in which the two carbon atoms are connected by
a double bond is called an alkene.
The general formula of an alkane is CnH2n where n is the number of carbon atoms in its one
molecule.
If an alkene has 2 carbon atoms in its molecule, then n = 2, and its molecular formula will
be C2H2×2 or C2H4.
If an alkene has 3 carbon atoms in its molecule, then n = 3, and its molecular formula will
be C3H2×3 or C3H6.
If an alkene has 4 carbon atoms in its molecule, then n = 4, and its molecular formula will
be C4H4×4 or C4H8
Alkenes are also called olefins because they react with chlorine to produce oil-like
derivatives (ole fins means oil forming)
2. Alkyne: An unsaturated hydrocarbon in which the two carbon atoms are connected by
a triple bond is called an alkyne.
The general formula of alkyne is CnH2n-2 where n is the number of carbon atoms in one
molecule of the alkyne.
If an alkyne has 2 carbon atoms in its molecule, then n = 2, and its molecular formula will
be C2H2×2-2 or C2H2.
If an alkyne has 3 carbon atoms in its molecule, then n = 3, and its molecular formula will
be C3H2×3-2 or C3H4.
The unsaturated hydrocarbons containing triple bonds (alkynes) are also called after the
name of the first member of the series called acetylene. Thus, the simplest alkyne is ethyne
having the molecular formula C2H2.
Common system of nomenclature of hydrocarbons
1. Trivial System: It is the system of giving name of organic compound by knowing the
source of the compound, e.g. methane was named after marsh gas. It is therefore the
system of giving name without any scientific rules and values. It is called common system
of nomenclature.
2. IUPAC System: It is the name given by International Union of Pure and Applied
Chemistry. This is an organization which gives the system of homenclature on naming
of hydrocarbons. According to IUPAC system of nomenclature, hydrocarbons are named
with two parts, i.e, word root + suffix. The word root shows the number of carbon and the
suffix shows the number of carbon-carbon bond in any hydrocarbon.
Depending upon the number of carbon atoms following word roots are used:
Blooming Science Book 10 179
No. of Carbon Root word Number of Word roots
carbon atoms
1 Meth 6 Hex
2 Eth 7 Hept
3 Prop 8 Oct
4 But 9 Non
5 Pent 10 Dec
On the basis of number of carbon- carbon bond following suffix are used:
Hydrocarbon Number of c - c bond Suffix
Alkane Carbon-carbon single bond − ane
Alkane Carbon-carbon double bond − ene
Alkane Carbon-carbon triple bond − yne
The names and structural formulae of some alkanes with their IUPAC names are given below:
Name of alkane (IUPAC name) Structural formula Molecular Condensed formula
(Saturated hydrocarbon) formula
1. Methane H CH4 CH4
HCH
H
2. Ethane HH C2H6 CH3–CH3
HCCH
HH
3. Propane H HH C3H8 CH3–CH2–CH3
H CCC H
H HH
4. Butane HH HH C4H10 CH3–CH2–CH2–CH3
H CC CC H
HH HH
5. Pentane HH HHH C5H12 CH3–CH2–CH2–CH2–CH3
H CC CC C H
HH HHH
The names and structural formulae of some alkanes with their IUPAC names are given below:
Common name IUPAC name Structural formula Molecular Condensed formula
formula
of alkene of Alkene
Ethylene Ethene HC CH C2H4 CH2=CH2
HH
180 Blooming Science Book 10
Propylene Propene H C3H6 CH3–CH=CH2
Butylene Butene HC C CH
C4H8 CH3–CH2–CH=CH2
HHH
HH
HCCC CH
HHH H
The names and structural formulae of some alkynes with their IUPAC names are given below:
Common name of IUPAC name Structural Molecular Condensed
alkyne of alkyne formula formula formula
Ethyne CH CH
1. Acetylene HC CH C2H2
Propyne CH3–C CH
2. Methyl acetylene H C3H4
HC C CH
3. Dimethyl acetylene
H
Butyne HH C4H6 CH3–CH2–C CH
HCCC CH
HH
Functional Group
A functional group is an atom or group of atoms which defines the structure of a particular
family of organic compounds.
Name of functional group Structure Class of the functional organic compound
1. Hydroxyl -OH alcohol
2. Carboxyl acid
3. Divalnt oxygen (ether) -COOH ether
4. Aldehyde -O- aldehyde
5. Amino amide
6. Keto -CHO- Ketone
-NH2
>C=O
Alkyl group combines with functional group to from different classes of organic compounds.
Example: Functional Group Compound
-OH CH3OH (Methyl alcohol)
Alkyl group C2H5COOH(Propionic acid)
1. CH3- -COOH CH3CHO (Acetaldehyde)
2. C2H5- -CHO C2H5-O-C2H5 (Ether)
3. CH3-
4. C2H5- -O-
Blooming Science Book 10 181
Homologous Series
A series of organic compounds having similar functional group that can be represented by same
general formula is called homologous series.
When the members of a class of related chemical compounds having similar structures are
arranged in order of increasing molecular weight, they are said to constitute a homologous series.
Each member of such a series is called homologue of the adjacent member. For example, the
alkanes like methane (CH4), ethane (C2H6), propane (C3H8), etc. form a homologous series in
which each member differs from next by CH2. In other word, a homologous series is a group
of organic compounds which contains the same functional group but has different chain length.
All these compounds have same chemical properties and can be prepared by similar method.
Characteristics of Homologous Series
1. All the members of the series can be represented by a general formula. For example, the
series of alkanes can be represented by a general formula CnH2n+2.
2. The adjacent members of a homologous series differ in their formulae by CH2.
3. All members of the series show similar chemical properties.
4. All members of the series can be prepared by general methods of preparation.
5. All members can show a gradual change in their physical properties such as specific
gravity, melting point, etc.
Molecular Formula, Structural Formula & Condensed Formula H
The chemical formula which shows the number of atoms of different elements
present in one molecule is called molecular formula. The molecular formula of H C H
methane is CH4. It shows that one molecule of methane contains one carbon atom
and four hydrogen atoms. H
The chemical formula which shows the structure of a molecule is called structural formula. The
structural formula of methane is along side.
The shorthand representation of structural formula is called condensed formula. Usually in
organic chemistry condensed formula is written because of molecular formula may not specify a
particular compound and writing structural formula is time-consuming. The condensed formula
of ethane and proparic are CH3-CH3 and CH3-CH2-CH3 respectively.
Some hydrocarbons and their compounds
Methane (CH4)
Molecular formula: CH4
Condensed formula: CH4 H
Structural formula :
HCH
H
Introduction: Methane is the first member of the alkane homologous series. In fact methane is the
simplest hydrocarbon. A molecule of methane consists of one carbon and four hydrogen atoms.
Sr
182 Blooming Science Book 10
Methane occurs as a natural gas along with petroleum deposits under the surface of the earth. The
natural gas coming out from the petroleum wells contains about 90 percent of methane and is used as
domestic fuel. In fact, natural gas is the biggest source of methane. Methane is also called 'marsh gas'
because it is found bubbling from marshy places, where it is formed by the action of bacteria on plants.
Structure of Methane Molecule:
The atomic number of carbon is 6, so we find that carbon atom has 4 electrons in the outermost
shell. Therefore, it needs 4 more electrons to complete the outer octet and become stable. As 4
hydrogen atoms combine with one carbon atom, its outer octet is fulfilled and it becomes stable.
C + 4H H H
H C H or
One carbon Four hydrogen HCH
H
Atom atom H
Methane Methane
(electronic formula) (structural formula)
Carbon is tetravalent. Each hydrogen atom shares one electron, so the valency of hydrogen is 1.
That is, hydrogen is monovalent.
Physical Properties
1. Methane is a colourless, odourless and tasteless gas.
2. It is lighter than air, being almost half as heavy as air.
3. It is insoluble in water
4. To some extent, it dissolves in non-polar solvents like ether, alcohol and carbon
tetrachloride.
5. Just like carbon dioxide, it also contributes to the green-house effect since methane
molecules also trap the outgoing heat radiation from the earth. [A molecule of methane
can trap heat energy 20 times more than a carbon dioxide molecule.]
(substitution ≅ displacement)
6. Its melting point is 184oC and boiling point is 161oC.
Uses of Methane:
1. Methane is an excellent fuel for domestic cooking.
2. Methane is used for preparing carbon black needed as filler in rubber industry.
3. Methane is used in the preparation of a variety of organic compounds like Methyl
chloride, (CH3Cl) Dichloromethane or Methylene dichlorine, (CH2Cl2) Trichloromethane
or Chloroform,(CHCl3) Tetrachloromethane or Carbon tetrachloride, (CCl4)
Methyl alcohol (CH3OH) and formaldehyde, (HCHO).
4. It can also be used for manufacture of hydrogen.
Blooming Science Book 10 183
Ethane (C2H6)
Molecular formula: C2H6
Condensed formula: CH3 - CH3
HH
Structured formula: H C C H
HH
Introduction: Ethane is the next higher homologous compound of methane. It occurs with
methane in natural gas, coal gas, etc. but in comparatively smaller amounts (approx, 10%).
Physical Properties
1. Ethane is a colourless, odourless gas.
2. Its boiling point is -88.3oC and melting point is -172oC.
3. It is sparingly soluble in water but readily soluble in organic solvents like alcohol, acetone,
ether, etc.
Uses of Ethane:
1. It is used as fuel and is the luminous constituent of natural gas and coal gas.
2. It can be used for welding purpose.
3. It can be used to prepare carbonic compound like ethyl chloride.
Propane
Molecular formula: C3H8
Condensed formula: CH3 CH2 CH3
H HH
Structured formula: H C C C H
H HH
Introduction: It is the third member of alkane series and heavier the ethane. It occurs in natural
gas and in gaseous fraction of petroleum distillation.
Physical Properties:
1. Propane is a colourless and odourless gas.
2. It is insoluble in water but it is soluble in organic solvents like alcohol.
Uses of Propane
1. This gas is used as fuel in gas lighters.
2. This gas is used in cooking action in petroleum industry.
3. It is used to make other carbonic compounds.
4. It is used as a cooling agent in petroleum industry.
184 Blooming Science Book 10
Butane (C4H10)
Molecular formula : C4H10
Condensed formula : CH3 CH2 CH2 CH3
Structured formula
HH HH
:H C C C C H
HH HH
Introduction: Butane occurs in natural gas whereas higher hydrocarbons are found in petroleum.
It is the fourth member of alkane.
Physical properties of Butane
1. Butane is a colourless, odourless, gaseous compound of carbon and hydrogen. Its chemical
formula is C4H10. Butane occurs in natural gas and in crude petroleum and is formed in
large quantities in the cracking of oil, to produce gasoline or petrol.
2. It is insoluble in water but soluble in ether and alcohol.
Uses of Butane
1. Butane is used in cooking gas (LPG) by mixing with methane.
2. It is used in rubber industry to manufacture synthetic rubber.
Isomers and Isomerism
The organic compounds having similar molecular formula but different structural formula are
called isomers.
The properties of organic compounds to exist in two or more isomers is called isomerism.The
hydrocarbons having four or more carbon atoms can exist in the form of isomers.
For example; the isomers of butane and pentane are given below:
Butane
Molecular formula : C4H10
HH HH (n - butane)
H C C C C H or CH3 - CH2 - CH2 - CH3
HH HH
H
HH C HH CH3
H C C C H or CH3 - CH - CH3 (iso - butane)
HH H
Pentane
Molecular formula - C5H12
Isomers
Blooming Science Book 10 185
H H H HH
HC C C C C H or CH3 - CH2 - CH2 - CH2 - CH3 (n- pentane)
H H H HH
H
HH C H H H CH3
HC C C CH
or CH3 - CH2 - CH3
H H HH ISO-pentane
H H CH3
HH C
C H or CH3 - C - CH3
HC C
H H CH3
HC H
H
neo-pentane
Alcohol
Alcohols are the hydroxyl derivatives of alkanes. So, alcohol is
defined as an organic compound containing the hydroxyl group C OH
(-OH) attached to a saturated hydrocarbon. For example, methyl
alcohol (CH3OH), ethyl alcohol (CH3CH2OH) etc. The hydroxyl Saturated
(-OH) group bonded to a saturated carbon is the functional group of carbon
alcohol. Functional
group
The name of alcohols are given according to the number of hydroxyl
group in the molecules. On the basis of number of hydroxyl(-OH) groups present in alcohol,
there are three types of alcohol. They are; monohydric alcohol, dihydric alcohol and trihydric
alcohol.
Monohydric alcohol
The alcohol having only one hydroxyl group is called monohydric alcohol. It is formed by
replacing one hydrogen of alkane by hydroxyl group. For example, methyl alcohol(CH3OH),
ethyl alcohol (C2H5OH), propyl alcohol (C3H7OH), etc.
H H H
HCH + OH H C OH (CH3OH)
H H
Methane Methyl alcohol
(monohydric alcohol)
186 Blooming Science Book 10
HH HH
H C C H H H C C OH (CH3CH2OH)
HH + OH HH
Ethane Ethyl alcohol
(monohydric alcohol)
Dihydric alcohol
The alcohol having two hydroxyl groups is called dihydric alcohol. It is formed by replacing
two hydrogen atoms of alkane by two hydroxyl groups. For example, Ethylene glycol.
HH 2H OH OH (CH2OHCH2OH)
HC C H + 2OH HC C H
HH HH
Ethane Dihydric alcohol (ethylene glycol)
Trihydric alcohol
The alcohol having three hydroxyl groups is called trihydric alcohol. It is formed by replacing
three hydrogen atoms of alkane by three hydroxyl groups. For example, glycerol.
HH H OH OH OH
HCC CH
H C C C H 3H (CH2OHCHOHCH2OH)
+ 3OH HH H
HH H
Propane Glycerol
In our daily life the word alcohol is synonymously used for ethyl alcohol. It is also called ethanol.
It is contained in alcoholic beverage like wine, whisky, beer, etc.
Some Important Alcohols and their uses
Methyl Alcohol
Molecular formula: CH3OH
Consensed formula: CH3OH
H
Structured formula: H C OH
H
IUPAC name: methanol
Methyl alcohol(methanol) is the first member of monohydric alcohol. It is prepared on
the industrial scale from methane obtained from natural gas. It is formed by replacing one
hydrogen of methane by hydroxyl group.
Blooming Science Book 10 187
Uses
1. Methyl alcohol is used as excellent solvent for fats, oil, paints, varnish, etc.
2. It is used for dry cleaning .
3. It is used as antifreeze for automobile radiation.
4. It is used for the manufacture of methyl chloride, formaldehyde, diethyl sulphate, etc.
5. It is used to make perfume, paint, medicine and synthetic fabrics.
6. It is used as fuel in spint lamp since it produces heat without smoke.
Ethyl Alcohol
Molecular formula: C2H5OH
HH
Structured formula: H C C OH
HH
Condensed formula: CH3-CH2OH
IUPAC name (Ethanol): Ethanol
Ethyl alcohol (Ethanol) is the earliest representative of the class. It is simply called alcohol. Its
IUPAC name is called ethanol. It is an important alcohol.
Alcohol is prepared by the partial oxidation of glucose in the presence of yeast. This is called
fermentation. The yeast produces enzyme zymase, that converts glucose into alcohol.
C6H12O6 Zymase C2H5OH+2CO2
(ethyl alcohol)
Uses of ethyl alcohol
1. Ethyl alcohol is used in the manufacture of alcoholic beverages.
2. It is used as a fuel in spirit lamps and stoves to produce heat.
3. It is used as a preservative for biological specimens.
4. It is used for the manufacture of terylene, ether, chloroform, iodoform etc.
5. It is used as fluid in thermometer.
7. It is used as a solvent for fat, oil resins etc
8. It is used in the manufacture of good quality of soaps and cosmetics.
Glycerol
Molecular formula: C3H5(OH)3
OH OH OH
Strucuture formula: H C C C H
H HH
Condensed formula : CH2OH-CHOH-CH2OH
188 Blooming Science Book 10
Introduction: The word glycerol is derived from”glyceros” means sweet. It is a trihydric alcohol.
The compounds containing three hydroxyl groups are known as trihydric alcohols. These three
hydroxyl groups must be attached to three different carbon atoms for stability of the compound.
The most important trihydric alcohol, which is also the first member of the series is glycerol
known as propane-1, 2, 3- triol in IUPAC system.
Glycerol may be considered as a derivative of propane, obtained by the replacement of three
hydrogen atoms from different carbon atoms by three hydroxyl groups. However, in industry
it is known as glycerine. It was first discovered by Scheele in 1779 A.D who obtained it by the
hydrolysis of olive oil.
OH OH OH 3H OH OH OH
+3OH
H C C CH H C C CH
H HH H HH
Uses of Glycerol:
1. Glycerol is used a sweetening agent in confectionery, beverages and medicines.
2. It is used a preservative for fruits, tobacco, etc.
3. It is used in the preparation of good quality soaps and cosmetics.
4. It is used a lubricant in watches.
5. It is used a moisture conditioner for tobacco products.
6. It is used antifreeze in automobile radiators.
7. It is also used the preparation of non-drying inks, printing inks and stamp pad inks.
Glucose
Molecular formula: C6H12O6
Structural formula:
HC O
H C OH
HO C H
H C OH
H C OH
CH2OH
Glucose is derived from a Greek word “Glukus” which means sweet. Its chemical formula is
C6H12O6. It helps to produce ATP in the body.
The taste of glucose is sweet. Glucose is a carbonhydrate and monosachharide sugar. Glucose is
found in fruits and honey. It helps in transportation of free sugar in the blood of animals. It is used
as the main source of energy essential for cells. It also helps to maintain balance in metabolic
activities. Glucose is both beneficial and harmful for animals.
Blooming Science Book 10 189
High sugar level in blood causes diabetes and swelling of different parts of body. On the other
hand, low sugar level in blood is also harmful for the body. Low glucose level causes dizziness,
fainting, vision problems, blurred speech, etc in our body. It causes hypoglycemia. Therefore,
there should be adequate amount of glucose in our body to live in a healthy life.
Let's Learn
1. Carbon forms covalent bonds because it has 4 free electrons in its outermost orbit and
shares same number of electrons of same or other elements to from covalent compound
(with single bond)
2. Glycol is a dihydric alcohol because it has two hydroxyl groups.
3. Methane is a saturated hydrocarbon because it has single covalent bond between carbon
and hydrogen atom.
4. Unsaturated hydrocarbons are more reactive than saturated hydrocarbons. It is because
double bonds or triple bonds between carbon atoms in unsaturated hydro carbons are
weaker than single boned between carbon atoms in saturated hydrocarbons.
Points to Remember
1. In the early days, chemistry was classified into two groups, organic and inorganic. Organic
chemistry is defined as the study of carbon compounds (except the oxides of carbon,
carbonates, bicarbonates and carbides).
2. Organic chemistry is the study of hydrocarbons and their derivatives.
3. Wohler synthesized organic compound (Urea) from ammonium cyanate (inorganic
compound) in the laboratory in 1828.
4. Most of the organic compounds contain carbon and hydrogen. In addition to that large
number of organic compounds contain oxygen and other elements too.
5. Organic compounds are studied separately because: (i) The number of organic compounds
is very large. (ii) The properties of organic compounds are entirely different from those of
inorganic compounds.
6. Sources of organic compounds are: plants and animals, coal and petroleum oil.
7. A compound made of hydrogen and carbon only is called hydrocarbon, eg. Methane,
ethane, butane, etc.
8. Hydrocarbons are: (i) saturated or (ii) unsaturated
9. A hydrocarbon in which the carbon atoms are connected by only single bond is called a
saturated hydrocarbon. Saturated hydrocarbon is also called alkane, e.g. Methane, Ethane, etc.
10. A hydrocarbon in which two carbon atoms are connected by a double bond or a triple
bond is called an unsaturated hydrocarbon, eg. ethylene (having double bond), acetylene
(having triple bond), etc.
11. Organic compounds have two names: common names and IUPAC names (IUPAC,
International Union of Pure and Applied Chemistry).
12. Methane gas occurs as natural gas along with petroleum deposits under the surface of the
earth. Methane is also called marsh gas.
13. Ethane has a molecular formula C2H6.
190 Blooming Science Book 10
14. Alkanes when subjected to high temperature and pressure break up into smaller fragments.
This process of decomposition of organic compounds by the application of heat is
terminated as pyrolysis.
15. Propanes formula is C3H8
16. Propane occurs in natural gas and in gaseous fraction of petroleum distillation.
17. One of the simplest classes of organic compounds which are made up of only carbon,
hydrogen and oxygen elements is alcohol.
18. The two simplest alcohols are: methyl alcohol and ethyl alcohol.
19. Alcohol are classified as primary, secondary or tertiary depending upon whether the
hydroxyl group is attached to a primary, a secondary or tertiary carbon atom.
20. Water gas is a mixture of carbon monoxide and hydrogen in a 1:1 ratio.
21. Methanol is a colourless liquid and is poisonous.
22. Ethanol (ethyl alcohol) is commonly called alcohol.
23. The compounds containing three hydroxyl groups are known as Trihydric alcohols. These
three hydroxyl groups must be attached to three different carbon atoms for stability of the
compound. The most important Trihydric alcohol, which is also the first member of the
series is glycerol known as propane-1, 2, 3- triol in IUPAC system.
24. Glycerol may be considered as a derivative of propane, obtained by the replacement of
three hydrogens from different carbon atoms by three hydroxyl groups.
25. Glucose is simply a type of carbohydrate. The carbohydrates are the chemical substance
formed naturally by green plants by the process of photosynthesis.
Project Work
To prepare various Hydrocarbon models
Materials Required:
Clay, toothpicks, colour, etc.
Method:
1. Make small balls of clay and colour them with a colour. These are carbon atoms.
2. Make even smaller balls of clay and colour with different colour. These are hydrogen
atoms.
3. Now join the carbon and hydrogen atoms as required with toothpicks to make the
models of different hydrocarbons.
Show these to your teacher.
Exercise
1. Answer the following questions.
a) What is organic chemistry?
b) How do you differentiate between organic chemistry and inorganic chemistry?
c) Why do we need to study organic compounds? Explain.
d) Distinguish between saturated and unsaturated hydrocarbons.
e) What are hydrocarbons? Classify them.
Blooming Science Book 10 191
f) What is a saturated hydrocarbon? Name two saturated and unsaturated
hydrocarbons each.
g) What is a structural formula? Write the structural formulae and two uses of:
i) Methane ii) Ethane iii) Propane iv) Butane
v) Ethene vi) Acetylene vii) Ethylene
h) What are the uses of methane?
i) What is isomerism? Illustrate with an example.
j) What are the characteristics of isomers?
2. What is alcohol? What are the two common alcohols?
3. What is meant by monohydric, dihydric and trihydric alcohol? Illustrate with examples.
4. What are the general properties of alcohol?
5. What are the uses of methyl alcohol?
6. What are the uses of ethanol?
7. What is a glycerol? Write its uses.
8. Write down the structural formulae, condensed formula and two uses of:
a. Glycerol b. Glucose
c. Bhutane d. Alcohol
9. Show with equation, the compound formed by the replacement of three hydrogen atoms
by three hydroxyl in propane. Also name the compound so formed.
10. Define homologous series. Write its feature.
11. What are functional groups?
12. Study the hydrocarbons and answer the questions.
c –c ≡ c- –c = c-
a) b)
i. Complete the structure formula and name them.
ii. Write the uses and common name of ‘b’.
iii. Which one is more reactive between ‘a’ and ‘b’ ? Why?
iv. What happens when sufficient hydrogen reacts with ‘a’? Show with equation.
13. Choose the correct alternatives from the following options.
i. The common name of ethyne is
a. Acetylene b. Ethylene c. Ethane d. Ethene
ii. Which alkane is used to make methanol?
a. Ethyne b. Butane c. Butene d. Methane
iii. The general formula of alkyne is:
a. CnH2n b. CnH2n-2 c. CnH2n+1 d. CnH2n+2
iv. The functional group of alcohol is
a. COOH b. O c. OH d. None of them
v. Which alkane is mostly found on petrol?
a. Methane b. Ethane c. Propane d. Butane
192 Blooming Science Book 10
Chapter Materials Used in Joseph Aspdin
Daily Life 1778 AD-1855 AD
13 (FirsMt Panourtflaacntdurcee)nent
Learning Outcomes Estimated Periods: 8+2
On the completion of this unit, the students will be able to:
explain the manufacturing process and uses of cement, glass, fiber, ceramics, plastic,
soap and detergents.
write the importance and uses of nitrogen, phosphorous and potassium containing
fertilizers.
state the role of compost fertilizer in agriculture.
describe pollution caused by different pesticides, synthetic cleaners and other chemicals.
list out preventive measures of chemical pollution.
identify the degradable and non-degradable wastes and their management.
Introduction
Chemistry is a branch of science which deals with structure, composition, physical and chemical
properties of substances that make up the universe. It involves how the substances undergo
changes and uses of the products resulting from chemical research, etc. In short, chemistry can be
defined as the branch of science, which deals with the scientific study of substances. Chemistry
has many major branches such as organic chemistry, inorganic chemistry, etc. Among the major
branches of chemistry, industrial chemistry involves the chemical production of raw materials
and the development, study and control of industrial chemical process and products. Industrial
chemistry plays a vital role in the production of tremendous variety of materials and chemical
products. They are used in the daily life of the people. Some of the major products of industrial
chemistry are cement, glass, synthetic fibres, ceramics, soaps, detergents, plastics, etc. In this unit,
we will study structure, properties and uses of some important products of industrial chemistry.
Cement
A cement is a binder, a substance that sets and hardens independently Fig: Cement plant
and can bind other materials together. Cement is used in construction
of buildings, bridges, roads etc.Cement is a complex mixture of
calcium silicate and calcium aluminate which when mixed with water
and dreis forms a hard structure. It is made by heating the mixture of
lime and special type of clay mixing in a ratio 2:1. Gypsum is also
added to increase the quality of cement which decreases the setting
time. Limestone forms the main source of lime and special type of
clay provides silica and alumina (SiO2 and Al2O3).
The manufacturing process of cement consists of the following three
basic steps:
i. Crushing and grinding
ii. Burning, and
iii. Finish grinding
Blooming Science Book 10 193
The limestone is crushed into small pieces of about 2 centimeters wide in the crushers. The two third
part crushed limestone and one third part of special type of clay are mixed and then ground into fine
particles in the grinders. Water is added during the process to get a soupy mixture called a Slurry.
The slurry is fed into a rotary kiln. The slurry moves slowly downwards as the kiln rotates. Oil or
powdered coal is burnt at the lower end of the kiln. This produces a flame that heats the air blown into
the kiln to about 1600oC. At this temperature the materials in the slurry undergo chemical change.
In the upper part of the kiln, most of the water in the slurry dries up, in the middle part limestone
decomposes to quicklime and carbon dioxide. In the lower part quicklime and clay combine
together to form calcium aluminates and calcium silicates. These aluminates and silicates are
mixed up to form small hard grayish particles called cement clinker.
The clinker is cooled and 2-3% gypsum (CaSO4.2H2O) is added to it. The mixture is ground to
powder which is called cement.
CaCO3 + Al2O3 + SiO2 → CaSiO3 + CaAl2O3
When water is added to cement, it hardens into a thick mass. This process is called setting of
cement. Quantity of gypsum is responsible for the setting time of cement.
Uses
Cement is the most important building material and it has the following uses:
i. A thick paste of cement, and water forms mortar. The cement is used to bind bricks and
plaster walls and roofs of the buildings.
ii. Concrete is a mixture of cement, sand, gravel and water. It becomes extremely hard on
setting. Concrete is used for making floors of the houses.
iii. Cements is used to construct and repair buildings, bridges, dams and roadways. RCC
(Reinforced cement concrete) is the concrete having framework of iron rods inside acting
as a support and is used making the roofs and pillars of the building and bridges.
Ceramics
Ceramics are useful materials from which different items such as pottery, bricks, earthen pots,
tiles, glassware, etc are made. These are made from clay and then baked. The clay used in making
ceramic is mainly a hydrated aluminum silicate (A12O3. SiO2, 2H2O). It contains other substances
like carbonate of magnesium and calcium and iron oxide. The pure white soil which is used to
make ceramics is called kaolin.
Making of clay-ceramic products
The clay and other minerals used in ceramics are crushed and ground into fine particles and
sieved. It is then mixed with water to produce a thick paste that can be shaped.
The clay is given the desired shape on a potter’s wheel or it may be casted in moulds of various
shapes. The dried products are heated in special furnaces called kilns. The products are heated at
high temperature. Heating hardens the things permanently and gives them strength and durability.
The earthenware so made are hard but brittle. They are porous and absorb water. They can withstand
high temperature. Some ceramic products are coated with tin oxide (SnO2) or lead oxide (PbO)
and then again heated. The coating melts and forms a film over the surface. This process is called
glazing which makes the surface smooth and water proof. The glazed pots are easy to clean. Colour
194 Blooming Science Book 10
and polish may be used to make the ceramics more attractive. The glazed pots can be decorated by
painting flowers and other designs over them with metal salts.
Properties of ceramics Scan for practical experiment
1. Ceramics can withstand high temperature.
2. They are poor conductor of heat and electricity.
3. They are resistant to chemicals and are brittle.
4. They are non-porous and non-sticky.
Uses visit: csp.codes/c10e15
1. Clay ceramics are used to make bowls, cups and plates.
2. Some ceramics are used to make artificial teeth and bone joints.
3. Common ceramics are used as insulators in spark plugs, an electric power lines and in
television sets.
4. Most ceramics are used as refractories. They are used in lining the inner surface of furnaces.
Glass
Glass is any solid substance that solidifies from the molten state without forming crystals. It
is actually a super-cooled liquid which means that it is cooled below its melting point before
it solidifies. The molecules in them are flowing very slowly from higher level to lower in a
vertically placed mirror. So, the glasses of old window are thick at the bottom and thin at the top.
Glass is an amorphous, transparent and hard homogeneous substance. It is the homogeneous
mixture of silicates of alkali metals and silicates of alkaline earth metals.
Glass is a wonderful material made by man. So many things around us such as windows, mirrors,
milk bottles, laboratory apparatus such as camera, binocular, telescope and microscope have
lenses made of glass.
The essential constituent of glass is silica (SiO2). It occurs as quartz or as sand and sandstone in
impure form. It melts at a temperature of about 1600oC.
Glasses used for different purposes have different properties. Some glasses are weak, others are
strong. Some are colourless while many others are coloured. Some are heat resistant and other
are not. These properties of glass depend upon the constituents. Some important glasses are
mentioned below.
Silica Glass or Quartz Glass
When silica is heated to about 1600oC, it melts and slowly cooled to form solid. Such glass is
called silica glass or quartz glass. Pure silica glass is very expensive. It does not break even if
heated to red hot and dipped in ice-cold water. Laboratory apparatus, electric devices, windows
and antenna shields for space vehicles are made from this type of glass.
Pure silica 1600oC Quartz glass
Water glass
It is made by heating the mixture of silica and sodium carbonate or potassium carbonate to above
800oC. On heating silica and sodium carbonate or potassium carbonate react to form sodium
Blooming Science Book 10 195
silicate or potassium silicate. It is soluble in water, so is called water glass.
SiO2 + Na2CO3 D Na2SiO3 + CO2
(Sodium silicate)
SiO2 + K2CO3 D K2SiO3 + CO2
(Potassium silicate)
It is used in making fire proof materials and silica garden. A solution of water glass is also used
for making pastes, gums and adhesives.
Ordinary Glass( Soda Lime or Soft Glass)
It is the most common type of glass. It is made by fusing a mixture of silica (50%), sodium
carbonate (15%), calcium carbonate (10%) and glass pieces (25%) at about 1500oC in a special
type of furnace. Limestone is added to make the solution insoluble and broken glass pieces to
help in melting. The mixture melts into a viscous liquid. The clear viscous liquid is poured into
moulds or blown with iron pipes to make glass-wares of various shapes. The prepared glass
articles are cooled slowly. The process is called annealing. If annealing is not done, the glassware
becomes easily breakable when something hot or cold is in it.
2SiO2 + Na2CO3 + CaCO3 D Na2SiO3. CaSiO3 + 2CO2
Soda-lime glass
The glass thus made is called soda lime glass. It is also called soft glass, as it softens easily on heating.
It is the cheapest of all types of glass. It is used for making bottles, light bulbs, window panes,
glass sheets and several other useful objects. Window glass is made by adding little amount of
lead monoxide to the mixture used for making soda-lime glass. Lead monoxide reacts with silica
to form lead silicate, which increases the refractive index of the glass. Lens, prisms, etc are made
from this type of glass.
Hard Glass or Potash Lime Glass
It is made by fusing a mixture of potassium carbonate, calcium carbonate and silica. It is a
mixture of potassium and calcium silicates. So this type of glass is called potash lime glass.
It has high melting point and can withstand high temperature. It is used for making hard glass
laboratory apparatus, tube lights, etc.
2SiO2 + K2CO3 + CaCO3 ∆ K2SiO3.CaSiO3 + 2CO2
(Potash lime glass)
Borosilicate Glass or Pyrex Glass
It is made by fusing a mixture of silica, sodium carbonate, calcium carbonate and boric oxide.
It is commonly known as pyrex. It is resistant to chemicals and heat. Therefore laboratory
apparatus such as test tubes, beakers, flasks, condensers and kitchen wares which are used at
high temperature are made from it.
5SiO2 + Na2CO3 + CaCO3 + B2O3 ∆ Na2SiO3.CaSiO3.B2(SiO3)3 + 2CO2
(Borosilicate glass)
Lead Crystal Glass
It is made by fusing lead monoxide and potassium carbonate with silica. It is a mixture of
196 Blooming Science Book 10
potassium silicate and lead silicate. This type of glass has high refractive index. So apparatus
like hard glass test tube, prism etc. are made from it. It is also used to make expensive drinking
glasses, lenses and T. V. and radar tubes.
2SiO2 + PbO + K2CO3 PbSiO3.K2SiO3 + CO2
(Lead crystal glass)
Coloured Glass
Coloured glasses are made by adding small amount of oxides of metals to molten glass. Different
metallic oxides give different colours to glass. Some of the metallic oxides and the colours
imparted by them to glass are given in table.
Metal oxides and coloured imparted to glass
Colour imparted to glass Metal oxide used
1. Blue Cobalt oxide
2. Black Nickel oxide
3. Green Cupric oxide, Chromium oxide
4. Purple Manganese dioxide
5. Yellow Ferric oxide
6. Red Cuprous oxide
7. White Tin oxide
Coloured glass is used for making sun glasses, signals for automobiles, trains and aeroplanes and
for decorative purposes.
Fibres
Fibres are hair like strands which are strong, flexible and extremely long in comparison to its
width. The fiber strands are known as yarns. Yarns is used to make fabric either by weaving of
knitting fibres. They are of two types:
1. Natural fibres
2. Artificial fibres
Natural fibers
The fibres mainly found from animals and plants are natural fibers. They include cotton, silk,
wool, pulp etc.
Wool and silk are used for making cloth. We get wool from animals and silk from silk worm.
Cotton is used for making clothes where as jute is used for making sacks, bags, ropes etc.
Artificial fibres
The fibres that are synthesized by using different chemicals are artifical fibres. They are strong
and more convenient to use. They do not shrink on washing. They are not attacked by insects
and moulds. They are easy to wash, dry up quickly and do not require ironing. They are cheap.
Some of the artificial fibers are made from natural substances. Rayon is made from cellulose.
Others such as nylon and terylene are made from synthetic substances.
Blooming Science Book 10 197
Cellulose is a natural polymer. It forms the main constituent of cell wall in plant cells. Wood
contains large amount of cellulose. Cotton and jute are two natural fibers made of cellulose.
There are two types of artificial fibres (a) Synthetic fibres and (b) Recycled fibres.
(a) Synthetic fibres
Arificial fibres made by chemical processes are called synthetic fibres. Some examples
are:
1. Nylon : It is the first true synthetic fibers made in 1930s. Nylon was first marketed in
New York and London and derives its name from these two cities.
Nylon is made by polymerization reaction of adipic acid and hexamethylene. After
polymerization reaction the nylon is extruded to form a fibres, which is then stretched.
The molecules of nylon are long chain molecules. The extrusion and stretching help to
make the molecules to line up along the fibres. When this happens the fibres becomes
strong and elastic. Nylon also has a very high tensile strength and is flexible.
Nylon does not rot and does not absorb water and sweat, it is air resistant. It is used in
making clothes, tooth brush bristles, climbing ropes, fishing nets, parachutes, motor tyres,
tennis racket strings and umbrella cloth.
2. Terylene fibers: Terylene fibres such as polyester, fortrel, kodel, etc. are durable and
quickly regain their shape after being wrinkled. They are strong, very resistant to the
action of chemical and biological agent. They have low water-absorbing property. It is
used for making suits when blended with cotton fibres (terycot) and wool (treywool).
Polyester fibres show wash-and-were properties.
3. Acrylic fibers: Includes creslan, orlon, etc. It resembles wool like so it is used to make
gloves, socks, etc.
b. Recycled fibres
The artificial fibres made by recycling the natural fibres are called recycled or regener-
ated fibres. For example: Rayon
Rayon (Artificial silk): It is the first man-made fibres used for clothing. It is made by
polymerization of cellulose (wood pulp or cotton wastes) and ethnic acid (solvent). It resembles
to silk fibres. So, it is called artificial silk. It is used in making bandages (gauze) because it does
not stick to the wounds. It is also used for making tyre cord, carpets (mixed with wool), caps and
aprons.
Advantages of Synthetic Fibres
1. Synthetic fibres can be produced on a large scale and hence they cost less.
2. These fibres are strong, durable and shining.
3. These require less care and do not need frequent ironing as they are wrinkle free.
Disadvantages of synthetic fibres
1. Synthetic fibres do not absorb sweat. So in hot weather they stick to the body making one
feels uncomfortable.
2. Some synthetic fibres such as nylon, terylene etc. catch fire more readily than cotton and wool.
198 Blooming Science Book 10
Insecticides
Pesticides
The harmful living organisms such as insects, rats, fungi and many others are called pests.
Pesticides are the chemicals which are used to control or kill pests. The pesticides especially
used to control weeds and harmful insects are called weedicides and insecticides respectively.
Similarly, rodenticides, maticides, nematocides and fungicides etc are used to control rats, round
worms and fungi respectively. Pesticides protect the plants from harmful organisms.
Insecticides
The poisonous chemicals manufactured or made and used to destroy or kill harmful insects are
called insecticides.
Insecticides are of two types. They are:
1. Organic insecticides 2. Inorganic insecticides
Organic insecticides
Organic insecticides are synthetic compounds which are composed of carbon, hydrogen and
oxygen. Organic insecticides are further divided into three types. They are:
1. Organochlorine compounds are stable compounds. They are aldrine, dichlorodiphenyl
trichloroethane (DDT), Benzene hexachloride (BHC) etc.
2. Organophosphate compound; e.g. malathion and parathion are the examples.
3. Carbamates contain amino group (-NH2). Termic and began are the examples.
Inorganic insecticides
Inorganic insecticides are usually made from minerals like calcium arsenate, lead arsenate,
fluorides, lime and sulphur. These insecticides protect cotton, fruit and vegetables from insects.
Advantages of using insecticides
1. They kill harmful insects quickly.
2. They are used to increase food production by killing or controlling the harmful insects.
3. They are used to control diseases. For example, mosquitoes are destroyed by the use of
insecticides.
4. The insecticides can kill the useful insects like honeybee also.
Disadvantages of insecticides
1. The continuous use of insecticides develops resistance in various insects.
2. Insecticides can seep into oil and drain into rivers and lakes and can pollute the water.
3. DDT pollute environment and reduces fertility of birds and fish and causes cancer to
mankind.
4. The insecticides can kill the useful insects like honeybee also.
Blooming Science Book 10 199
Precautions
All the insecticides are poisonous so they should be handled carefully. We should select those
insecticides that do not affect the plants and other. We should not use insecticides more than
enough. We must cover our mouth and nose while working with it.
Fertilizer
Plants absorb elements such as Phosphorous, Potassium, Calcium, Boron, Chlorine, Iron, etc.
from soil. This is just like borrowing elements from soil, because the elements are returned to
the soil after the death of living beings. This situation occurs only in the natural ecosystem like
forest. In the cultivated land, the growing plants use the nutrients from the soil. After harvesting
the crop, the nutrients are not returned back to the soil. Repeated growing of the crops consume
a lot of these nutrients from the soil. This results in decreasing in minerals or nutrient from the
soil. Rain water and erosion also decrease nutrients. As a consequence; land fertility decreases
and the growth of the plants as well as their yield become poor. The addition of fertilizers make
up for the loss of these nutrients. Thus, the fertilizers are the substances (chemical compounds)
which are added to the soil to replenish the nutrients removed by growing plants.
The essential elements present in fertilizer must be readily available to the plants. The essential
elements like oxygen, hydrogen and carbon are obtained by the plants from carbon dioxide of air
and water. But to supply the remaining elements, fertilizers have to be used.
Types of Fertilizers
There are two types of fertilizers
1. Organic fertilizers (manures) and 2. Inorganic fertilizers (Chemical fertilizers)
Organic Fertilizers (Manures)
Manures are organic substances obtained from the decomposition of dead plants and animals
remains. Compost is an organic fertilizer.
It is made by keeping dead plants and animals waste buried in a pit with alternating layer of soil.
The organic matter is decomposed by bacteria and fungi to give compost. Organic fertilizers
provid all the essential elements required for plants and also improve the soil quality. Vegetables
grow in compost are tasty and healthy.
Green Manures
Green Manures are the green plants which are grown, ploughed and mixed in the soil to
provide essential nutrients to the growing plants. Green manures supply essential elements
which are required for the growing plants and also check the soil erosion. The leguminous and
non-leguminous plants are grown, ploughed and decomposed to get organic matter which is also
called humus.
Compost Manures
Compost manure is an organic fertilizer which is made from dead, decayed and decomposed
parts of animals and plants or their waste products are kept in a pit with altering layers of soil.
Sometimes, little amount of lime is also added to the mixture. Due to microbial action, the
mixture gets decomposed into compost manure. It is used in the soil to provide essential elements
for the growing plants.
200 Blooming Science Book 10
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